Traffic control system



Aug. 3, Q 1 ER 7 2,088,697

TRAFFIC CONTROL SYSTEM Original Filed April 25, 1933 4 Sheets-Sheet lA-jrezsr a ,I H

INVENTOR. BY CHA2L5 0.6552

A TTORNEYS.

3, 1937. c. D. GEER 2,088,697

TRAFFIC CONTROL SYSTEM Original Filed April 25; 1950 4 Sheets-Sheet 2 uww eo 33 v .26 W i I /5/ lvsz INVENTOR.

\ CHA/zzzs D. 6552 A TTORNEYS.

1937- c. D. GEER 2,088,697

TRAFFIC CONTROL SYSTEM Original Filed April 23, 195:) 4 Sheets-Sheet sINVENTOR. C'HAQL E5 D. 6552 BY wMcLJ BoMJY/L/ j A TTORNEYS.

TRAFFIC CONTROL SYSTEM Original Filed April 25, 1953 4 Sheets-Sheet 4INVEN TOR. CHAQL 5a 0 6552 BY ,A e (S W, bmv rofi.

. A TfTOR/VEYS.

Patented Aug. 3, 1937 master PATENT oFFicr TRAFFIC CONTROL SYSTEMCharles D. Geer, New Haven, Conn, assignor to The Engineering & ResearchCorporation, (formerly The Stirlen Engineering & Research Corporation),a corporation of Connecticut Original application April 23, 1930, SerialNo. 446,480. Divided and this application April 7,

1936, Serial No. 73,156

10 Claims.

This invention relates to a traffic system capable of use in numerousdifferent associations but primarily intended for employment withvehicle lanes such as roadways, and particularly at points ofintersection of roadways, the present invention aiming to provide anautomatic system by means of which traflic will be expeditiously handledand which system to the greatest extent if not completely will becontrolled in its functionings by the presence of traffic along thevehicle lanes.

This application is a division of application Serial No. 446,480 filedApril 23, 1930, and relates particularly to and claims the periodic callfeature and a traffic control system embodying said periodic callfeature, both said feature and said system being disclosed but notclaimed in said application Serial No. 446,480.

The present application discloses but doesnot claim the speedproportional control feature of application Serial No. 446,480. featureis completely disclosed and claimed in application Serial No. 446,479filed April 23, 1930, by Frederick G. Kelly, Jr., which applicationissued on June 23, 1936, as Patent 2,044,907.

The present application also discloses but does not minimum delayperiods and in which moreover the system will embrace a factor of safetysuch that the danger of accidents between vehicles or between vehiclesand pedestrians will be reduced to a minimum, if not entirelyeliminated.

A further object is that of providing a system of this character, theseveral units of which will be individually simple and rugged inconstruction and embrace relatively few parts, these units whenassembled providing a system operating over long periods of time withfreedom from mechanical and/or electrical difficulties. Moreover, theseunits to the greatest extent will be capable of individual adjustment sothat while at the time of their manufacture, conditions may generally beapproximated, adjustments may be made at the time of or subsequent totheir installation at an actual trafiic intersection so as to take intoaccount the characteristics individual to the traflic flow along thevehicle lane comprising such intersection.

This latter A still further object is that of providing a trafficcontrol system in which in the functionings of the system, account willbe taken not alone of the density of the traffic but also of the speedwith which it is moving so that on the one hand undue delays will not beincurred and on the other hand, the danger of a relatively slow movingvehicle becoming trapped at the intersection will be reduced to aminimum.

Another object is that of providing a system in which even in theabsence of vehicular traffic, the system will function to permitpedestrians to traverse the intersection without danger.

A further object is that of providing a trafiic actuated right of waysignalling system for traffic lanes in which transfer of right of wayfrom either one traffic lane to another will be assured after arelatively long right of Way period in the one lane even in the absenceof traffic actuation on such other lane.

An additionalobject is that of providing a traffic actuated right of waysignalling system in which in the presence of trafiic right of Wayistransferred from one lane toanother in response to trafiic actuationand in which after arelatively long period of right of way on one tramclane with absence of trafilc actuation on another lane artificialactuation is produced on such other lane to simulate the effect oftraffic actuation on such other lane so as to 'cause'subsequent transferof right of way to such other lane.

Still another object is that of construction of a system, the severalunits of which will function in the event of one condition of traffic tosubstantially instantaneously transfer the right of way from one vehiclelane to the intersecting vehicle lane upon the approach of a vehiclealong the latter, but in the event of vehicles passing along the firstvehicle lane and approaching the intersection will delay thistransfer ofright of way for a period adequate to assure safety to transfer.

With these and further objects in mind, reference is had to the attachedsheets of drawingsillustrating one practical embodiment of the inventionand in which:

Figure 1 is a diagrammatic view showing a highway intersection employinga signal system embodying our invention;

Figure 2 is a detailed view showing a section of a vehicle actuatedcontrol device;

Figures 3 and 4 show diagrammatic representations of timing mechanisms;

Figures 5 and 6 are a diagrammatic view showing the circuits of anapparatus for operating the signal at intersecting trafiic lanes.

A self regulating automatic trafiic control system embodying myinvention may comprise three parts: a vehicle actuated control, trafficresponsive device or detector, placed in or at the side of a road orvehicle lane, an electrical time limiting control system, and a signaldevice to indicate right of Way to traffic. A function of the vehicleactuated control device is such that vehicles approaching on the severaltrafiilc lanes actuate various electrical control circuits. Theseactuations control the operation of the electrical time limitationcontrol system, which in turn 7 controls the right of way device. Theright of way device, to inform the traffic in each street when to go andwhen to stop,,may be the standard red, yellow and green lights now ingeneral use, but may also be any other convenient or desirable form. Thevehicle actuated control may be of several types as hereinaftermentioned:

One means actuated by the approaching vehicle may be of a mechanicalnature such as a mechanical switch located in or at the side of thestreet, an electrical contactbeing made upon passage of the vehicle.

Another means for detecting and recording the presence of anapproachingvehicle may be a beam of light projected across the highwayand received upon a photo-electric or light sensitive electrical cell,so that an approaching vehicle causes an interruption or fluctuation'inan electrical current passing through the photo-electric or lightsensitive cell.

An electrical magnetic device located in this street or at the side ofthe street may also be could be used.

ing a suitable warning signal, transfers right of way to B street. Bstreet now has the right of I way and vehicles approaching on it maycross the intersection. The rightof way will be transferred back to Astreet under any one of the.

' following conditions:

Condition I.-If a vehicle approaches on A street and all B- streettraflic has passed the intersection.

Condition II.If a vehicle approaches on A street and B street traffic isstill moving. at the end of a predetermined period, (such as 30 seconds)the right of way is transferred to A street.

Condition III.-If no vehicles approach on A f street, then afterpreferably a greater predeter mined period, whether or not traflic ismoving on B street, right of way will be called for on A street as if avehicle had approached there and right of way will be transferred to Astreet as under Conditions I and II above.

The various periodsare controlled by suitable timing mechanisms.

Provision to transfer the right of way to A street as outlined underCondition I above is accomplished thru the use of a timing mechanism onA street.

which provides sufiicient time for the individual B street vehicles tocross the intersection. This timing mechanism is reset toward itsstarting position each time a vehicle operates the B street actuatingmeans. Hence, if no further vehicles approach on B street, this timingmechanism will eventually complete timing the period it is set for; andwhen such time is reached, the

right of Way is transferred to A street. The action is of course similarwhen the. right of way is transferred from A street to B street.

To provide for Condition II mentioned above, in which continuous Bstreet trafiic must be interrupted, another timing mechanism is providedwhich is not reset by vehicles on B street, and which starts timing whenthe vehicle approached When it has timed the period it is set for, theright of way is transferred to A street.

To care for Condition III mentioned above,

there is provided another timing mechanism which starts timing B streetright of wayas soon as right of way appears on B street. When it hastimed the period it is set for, it callsfthe right of way to A street,similar to the way in which right of way would be called to A street bya vehicle approaching on A street and thus simulates the effect ofactuation of the vehicle actuated control on A street by such a vehicle.After right of way has been called in this manner, it will betransferred as outlined in either Condition I or Condition II, dependingupon conditions in B street.

When right of way istransferred as in Condition II, vehicles are on Bstreet which have not had sufficient time to cross the intersection,even though they have actuated the B street actuating;

means. The control system is left in such ,a condition that as soon as Astreet traffic permits, right'of way will be transferred to B streetwithout requiring any additional actuation of the B street vehicleactuated means.

The timing mechanism which is reset by trafific; is so arranged that itmay be reset in accord with the speed of the vehicle causing theresettingj And thus the time or protection period given each vehicle iscommensurate with the speed of the.

vehicle. In this manner, no vehicle receives an unnecessarily longprotection period; thus avoid ing needless delay in the interferinglane.

The chief function of the warning signal when it indicates to movingvehicles that they are about to lose right of way, and accordingly thevehicles must be brought to a stop. The warning signal thus acts as avery important safeguard.

Whenever right of way is transferred asout- But when right of way istransferred,-

longer warning signal should be given. This is.

accomplished by providing a mechanism which times the warning signal ina different way, de-

pending Whether the right of way is transferred :as outlined inCondition I, or whether it is transferred as outlined in Condition II.

If several vehicles have passed the actuating means while being giventhe stopv signal, some time will elapse, after they have been given theright of way signal, before the last of said vehicle-s gets into motion.This time may be quite considerable, and may exceed the protectionperiod provided by the resettable timing mechanism. There is accordinglyprovided an additional timing mechanism, the time period of which is.proportional to the number of vehicles that have passed the actuatingmeans, but are not allowed to proceed. This timing mechanism begins totime as soon as right of way appears on its street; and only after ithas finished timing its period, may the resettable timer begin tooperate.

While there has been described above the self regulating automatictrafiic control system em.- bodying this invention, and there has beenshown that this invention may comprise three interconnected parts, therewill now be described in detail the construction of one complete andspecific system embodying the invention:

Referring to Fig. 1 of the drawings, there is shown a complete selfregulating automatic traffic control system applied to intersectingstreets A and B. The vehicle actuated controls are indicated by thenumbers 2, 3 and 4. The signal means in this; particular embodiment is,as preferred, visual, and is indicated at 5. It embraces red and green.electric lamp reflectors or lenses visible from either direction on Astreet, but not visible on B street; red and green electric lampreflectors, or lenses, visible from either direction on B street, butnot visible on A street; and preferably a yellow electric lamp lens orreflector visible from both streets. The electrical time limitingcontrol is indicated by 6. The unshaded lines indicate controllingcircuits. the vehicle actuated devices in A street control theelectrical time limiting control 6, and so do the vehicle actuateddevices in B street. The time limiting control 5 controls the signal 5.

Fig. 2 shows one form of vehicle actuated device consisting of a ramp lhinged at 8 and forced into an elevated position by spring 9. The topsurface of the ramp may be substantially at the level of the street.When the wheel of a vehicle passes over the ramp, the weight of thevehicle depresses ramp 7, causing contacts IE! and H to be pressedtogether, closing circuit between wires I2 and 53. When the wheel leavesramp 7, spring 9 forces the ramp l into an elevated position, breakingcircuit between wires i2 and it by separating contacts iii and ii. Thevehicle actuated devices in A street are connected in parallel. Thevehicle actuated devices in B street are also connected in parallel.

The time limiting control uses several timing mechanisms. One embodimentof such a timing mechanism is shown in Fig. 3. When a source of voltagesupply is connected between wires I l and I5, current flows from wire l4thru wire 56, relay ii, and wire iii, to wire l5, operating relay ii.This allows current to flow from wire l4 through adjustable resistanceI8, contact 20, armature 2i, wire 22, wire 23, condenser 24,

wire 25, to wire I5. Thus the voltage of the supply is applied tocondenser 24 through resistance l9, and the voltage of the condenserbegins to build up at a definite rate determined by the size of thecondenser, the resistance l9, and the voltage of the supply. shuntingcondenser 24! is a circuit including a glow tube 25, and a relay 21. Theglow tube comprises a bulb containing a suitable gas into whichelectrodes 28 extend. This tube has such a characteristic that it isnormally non-conducting, but when the voltage across its terminalsreaches a certain critical or threshold value, the gas ionizes andbecomes a good electrical conductor and will not become conducting againuntil the voltage across its terminals has dropped considerably belowthe critical ionizing voltage. The voltage of the supply is greater thanthe critical voltage of the tube. When the voltage across the condenseris built up to the critical voltage of the tube, the tube suddenlybecomes conducting, causing current to flow momentarily'from condenser 2through tube 26, and relay 2i, causing relay 27 to operate. This wouldeffect only a momentary closure of the relay were it not for the lockingcircuit com.- prising contact 29, armature as, and wire 3!, which isestablished when relay 2? ope-rates. This places relay 2! directlyacross the supply, and relay 2i remains energized.

The interval elapsing between the application of the supply voltage towires I4 and I5, and the operating of relay El, is the period timed bythe mechanism. By suitable adjustment oi resistance is, any desiredinterval may be obtained. When relay 2' operates it may be used toactuate one or more armatures in addition to armature 38. Theseadditional armatures will be used as described below.

Relay 2? remains energized as long as the supply voltage is connectedbetween wires 14 and 55. If the supply voltage is disconnected, theenergizing circuits of both relay ii and relay 2? interrupted, bothrelays become deenergized and drop to their deenergized positions. Whenrelay I! becomes deenergized, it causes armature 2! to touch contact 32.This shunts adjustable resistance 33 across the terminals of condenser24, and any energy that may be stored in condenser 24 is dissipated inresistance 33. The rate of dissipation of energy may be varied at willby proper adjustment of resistance 33.

Wires M and I5 may be called conveniently the energizing wires of thetiming mechanism and are accordingly marked EE.

Connection I .-Figs. 5 and 5 combined show the wiring diagram of atrafiic control system embodying the invention. With thevariousswitches, in the positions indicated, the system is so arrangedthat right of way remains showing on the street which last had right ofway, in the event that there be no traffic on either street. Assumingthat A street last had right of way, instan taneous operating relay 3%will be energized, thus lighting the A street green light and B streetred light through wire 35, wire 35, contact 31, armature 38, and wire39. It will also be noted that timing mechanisms lil and i! areenergized, and also instantaneous operating relay 42. The action of theapparatus under various trafiic conditions will now be described.

Case ISing'le vehicle approaching on B street.Assume a vehicleapproaches on B street actuating one of the vehicle actuated deviceslocated there, closing circuit between wires 52 and I3. The B streetvehicle actuated control 'de vices are connected tb wires 43 and M; thuswhenever one of the B street vehicle actuated devices is actuated, theactuating circuit of relay 45 is closed and it operates. Thismomentarily closes the energizing circuit of relay 5.6 through wire it,wire 48, wire 59, contact 50, armature 5i and wire 52. Relay til causesarmature 92 to touch contact es, locking in relay 46 through wire 94,contact 95, armature 90, wire 9i and wire 62. This locking circuit isnecessary because relay 45 operates only momentarily, and were it notfor this locking circuit, relay 46 would also operate only momentarily.The operating of relay 46 interrupts the energizing circuit of timingmechanism 40, which has been made through wire 41, armature 53, contact54, wire 55, contact 56, armature 51, wire 58, wire 59, contact 60,armature 6 I, and wire 62. Timing mechanism 40, its energizing circuitbeing broken, allows its relay 21 to drop to its deenergized position,operating armatune 63. The energizing circuit of relay 34 which hadbeen'made through wire 64, armature 63, contact 65, wire 66, switch I45,wire 61, and the contact of switch I45, contact 66, armature 69, wire10, contact 1|, armature 12 and wire 13, is now broken by thedeenergizing of timing mechanism 40, and relay 34 drops to itsdeenergized position. Armature 38 separating from contact 31extinguishes the A street green light and B street red light. At thesame time, the yellow light is energized through wire 39, armature 38,contact 14, wire 15, wire 16, contact 11, armature 18, and wire 19. Atthe same time, timing mechanism 80 is energized through wire 8 I,armature 82, contact 83, wire 84, wire 05, armature 86, contact 81, wire88, contact 89, armature 90, wires 9| and 62. Timing mechanism 80 issimilar to the timing mechanism shown in Fig. 3, and. similarly, EErepresents the energizing wires. Assume that the resistance I9 in thistiming mechanism is adjusted so that the mechanism times an interval of3 seconds. When relay 34 was deenergized, it deenergized relay 42because the energizing circuit of relay 42, consisting of wire 13,armature 96,

4 contact 91, wire 98, wire 99, contact I00, armature 82, and wire 8|,is broken when armature 82 separates from contact I00. After timingmechanism 80 has been operating for 3 seconds, its condenser dischargesthrough its tube in the manner described above, and its relay,corresponding to relay 21 operates, causing armature IN to separate fromcontact I02, and to touch contact I03. When armature IOI leaves contactI02, it breaks the operating circuit of timing mechanism 4| and timingmechanism 4| becomes deenergized. The energizing circuit of timingmechanism 4| consisted of wire I 04, armature IOI, contact I02, wireI05, switch I06, Wire I01, contact I08, armature I09, and wire IIO. Whenarmature |I touches contact I03, relay III is energized through wireI04, armature IOI, ,contact I03, switch I46, wire 2, wire ||3, switchI46, contact II4, armature H5, wire II6, contact ||1, armature 53, andwire 41. Relay III operates armature 18. Armature 18 separates fromcontact 11 extinguishing the yellow light and touches contact II 8,lighting the B street green light and A street red light through wire19, armature 18, contact II8, wire H9 and wire I20. The right of way isnow being given to 13 street and the vehicle which approaches there maycross the intersection. Timing mechanism |2I is the mechanism whichprovides the necessary time for the individual vehicles on B street tocross the intersection. This timing mechanism is also similar to themechanism shown in Fig. 3,-EE representing the energizing'wires. Assumethat the resistance corresponding to resistance I9 is adjusted sothattiming mechanism |2I times a period of 10 seconds. The energizingcircuit of timing mechanism I 2| is made through wire 52, armature 5|,contact I22, wire I23, switch I24, wire I25, contact I26, armature 63and wire 64. It will thus be noticed that this circuit is completed whentiming mechanism 40 becomes de-energized.

Case II-Single vehicle approaching on A street immediately aftertransfer of right of way to B street.-The action of the apparatus issimilar to the action as described under Case I, up to the time right ofway is actually transferred to B street.

A street operates, for example, ramp 2. The

ramps in A street are connected across Wires I21- and I28, and thus thevehicle on A street causes a momentary operation of relay I29. Thiscauses relay 42 to operate by energizing it through wire I I0, armatureI09, contact I30, wire I3l, and wire 13. Relay 42 looks itself inthrough armature 96, contact 91, wire 98, contact I32, armature I33,wire I34 and wire 8|. Contact between armature I33 and contact I32 ismade because when relay I29 operated, it separated armature I09 fromcontact I08, thus breaking the energizing circuit of timing megchanism4|, which immediately dropped to its deenergized position. Assuming thatonly a single vehicle was approaching on B street, then, after 10seconds, timing mechanism |2I will operate and armature 90 will separatefrom contacts 95 and 89. In separating from contact 89, armature 90breaks the energizing circuit of timing mechanism 80 which becomesdeenergized, causing armature |0| to leave contact I03. This deenergizesrelay I I I, which allows armature 18 to separate from contact H8, extinguishing the B street green light and A street red light. At the sametime armature 18 touches contact 11, lighting the yellow light asdescribed above. ture 6| to touch contact 60, which reestablishes theenergizing circuit of timing mechanism 40. Timing mechanism 40 issimilar to the mechanism shown in Fig. 3; and We shall assume that itsresistance, corresponding to resistance I9, is so adjusted that themechanism times a period of 3 seconds. After being energized for 3Seconds,

The single vehicle now approaching on In deenergizing, relay III allowsarmatiming mechanism operates, separating arma-' ture 63 from contactI26, and allowing armature 63 to touch contact 65. In separating fromcon tact I26, armature 63 breaks the operating circuit of timingmechanism I2I, which becomes deenergized. At the same time, armature 63,in touching contact 65 energizes relay 34. Relay 34 operates armature38, which leaves contact 1 extinguishing the yellow light, and touchescontact 31, lighting the A street green light and B street red light,and the right of way is again being given to A street and the vehiclewhich approached there may cross the intersection.

The above two cases describe transfer of right of way from one street toanother in response to.

a vehicle approaching on this street where right of way is not beinggiven. It will be noticed that once a vehicle has been given right ofway, it will retain right of way for a certain minimum period, forexample, 10 seconds; and even though a vehicle approached on the otherstreet, right of way cannot be taken away until the end of this minimumperiod which we assume is suflicient time for the vehicle tozcross theintersection. If all traffic has ceased, then the timing mechanism whichprovides this minimum period, (for street A this would be timingmechanism 4|), is inits operated condition, and should a vehicleapproach on the other street, right of way will be transferredimmediately. If trafiic has not ceased, the above mentioned timingmechanism will not be in its operated condition, and should a vehicleap-.

proachon the other street, it must wait until this timing mechanism hasoperated.

Case III--Single vehicle approaching on street followed within tenseconds by a second vehicle on B street.Assuming the right of way isbeing shown to A street and there is. no traffic on A street, then thefirst vehicle approaching on B street will transfer right of way to Bstreet as described in Case I. If a second vehicle approaches on Bstreet, actuating either ramp or 3, this will cause relay' i5 to operatemomentarily breakingcincuit between armature 5i and contact I22. Thiswill break the energizing circuit of timing mechanism I2 I. We haveassumed that timing mechanism l2l times a period of 10 seconds. Assumingthe second vehicle to have approached within 10 seconds from the timethe first vehicle approached, condenser it of this timing mechanism willnot be charged up to the critical voltage of tube 26, and relay 2? willnot have operated. The breaking of the energizing circuit deenergizesrelay I7 and the charge which has accumulated on the condenser will bedissipated in resistance 33, as described previously. Relay 45 is ofcourse energized only for a short time, and consequently the energizingcircuit of timing mechanism l2i is immediately reestablis'hed. But itwill-be noticed that condenser 2t has been (lo-energized, andconsequently a full 10 seconds must elapse before the condenser willagain be charged to the critical voltage of tube 526. The operation ofthe system under Case II has shown that right of way cannot be takenaway from B street once it has received it, until timing mechanism l2!has operated. Thus, whether or not, in the meantime, a vehicle hasapproached on A street, the second vehicle that approached on B streetreceives a full 10 seconds in. which to cross the intersection. It isapparent that this operation will be repeated if additional vehiclesapproach on B street. As soon as vehicles cease approaching on B street,timing mechanism i2! will,-iaft er 10 seconds have elapsed since thelast actuatio'nof either ramp l or 3, operate, and assuming a vehicle tohave approached on A street,

the right of way will be transferred to A street, as described underCase II. Once right of way has been transferred to A street, theoperation or" the system, should more vehicles approach on A street, isprecisely as described above. Relay 529 performs the same function for Astreet that relay 35 performs for B street; and, similarly, timingmechanism 4i operates when right of 'way is being given to A street,just as timing mechanism l'Zl operates when right of way is being givento B street.

In describing Case III, it was assumed that after right of way wastransferred to B street, a vehicle approached on A street. If vehi lesapproach on A street, then after the last car has passed B street,timing mechanism l2l will operate and, right of way will simply remainon B street. -,This is because, even though the energizing circuit oftiming mechanism 8!! is interrupted when armature 9B separates fromcontact 89,

timing mechanism 80 remains energized because power continues to beapplied through wire -i35, contacti36, armature l2, and wire it. This isbecause, since no vehicle has approached on A street, relay 42 isde-energized. If vehicles should again come on B street, timingmecham'sm l2! will again be de-energized, as described above. The Bstreet traffic will again be pro tected and it cannot lose rightof wayuntil all of 7 113; hasassed ,the intersection. It is ap that as long asno Vehicles approach on A street, B street trailic can retain right ofway indefinitely.

Case IV-Continuous trajfic on B street with a. vehicle waiting on Astreet.When this condition occurs, timing mechanism I2l will becontinually deenergized or reset by the B street vehicles, and right ofway would remain indefinitely on B street. This is permissible if thereis no trafilc on A street. But should vehicles approach on A street,there must be some limitation to the length of time B street cancontinue to hold the right of way after vehicles have approached on Astreet. This is accomplished with timing mechanism I31. This timingmechanism is again similar tothe type shown in Fig. 3, and we shallassume that its resistance I9 is so adjusted that the mechanism times aperiod of 30 seconds. This timing mechanism does not begin to operateuntil a vehicle approaches.on A street. When this happens, relay 42becomes energized and current flows from wire l3, through armature 12,contact ll, wire I38, the energizing wires E--E of timing mechanism [37,wire i253, contact 526, armature 63, and wire $4. It will furthermore benoticed that this timing mechanism is not reset by vehicles on B street,and once energized, uninterruptedly continues to time until the end ofits timing period, for example, 30 seconds. Assuming B street traffic tobe continuous, then after 30 seconds, timing mechanism i3l will operatearmature 86, separating it from contact 8?. This deenergizes timingmechanism 8B which in turn. deenergizes relay :1 l i, and right of wayis transferred to A street as described above under Case II. Thedifference is that relay 46 remains energized because its lookingcircuit continues to bemade through contact 95 and armature 95, sincetiming mechanism [21 has not been energized long enough to operate.Thus, after right of way is transferred to A street relay 46 isenergized, which is equivalent to the approach of a vehicle on B street.The system thus provides that without requiring an additional actuationof either vehicle actuated control I or 3, right of way will return to Bstreet as soon as traffic on A street permits. This procedure isnecessary because a vehicle may approach on B street within .a second ortwo from the time right of way is going to be taken from B street, andnot having had sufficient time to cross the intersection, these B streetvehicles I would be stranded. The system is thus arranged so thatwhen'right of way is transferred, due to the operation of timingmechanism lZi, relay 46, during such a transfer, becomes tie-energized.-But, should timing mechanism l3! transfer right of way, relay 46 willnot become deenergized, and right of way will .thus be recalled to Bstreet, so that'vehicles on B street which did not receive a full; 10-seconds in which to cross the intersection, will be given ample time todo so. Timing mechanism i3i performs the same I function for A streetthat timing mechanism it? performs for B street; The energizing circuitof timing mechanism I 39 consists of wire 47, armaturetB, contact H1,wire Mil, energizing wires EE, wire Hi5, contact Hi2, armature Hill, andwire HM.

There. is thus provided a very flexible traflic control system; It isarranged that once right of way isgiven to a particular street, in re-'sponse to vehicles approaching there, each ve-.

hicle. receives a certain protection period from the timeit ac'tuatesthe ramp in the street, during whichit may cross the intersection, andis protected against opposing traiiic. If a vehicle approaches on thestreet where the stop sign is being given, right of way will betransferred to it immediately if traffic has ceased on the intersectingstreet. If traflic has not ceased, this vehicle must wait until thelastvehicle on the intersectingv street has had a full minimum period inwhich to cross the intersection. However, vehicles do not have to waitindefinitely should there be continuous traflic on the opposing street.The system provides that the vehicle need not wait more than a certainpredetermined time. At the end of this time, the continuous traflic onthe opposing street is interrupted to allow the waiting vehicle orvehicles to cross the intersection. The system, however, is left in sucha condition thatwithout requiring the approach of further vehicles, theright of way will eventually revert to the street where continuoustraffic was interrupted, to allow the-vehicles which did not havesuflicient timeto cross the intersection to do so.

In describing the operation of the. embodiment of the timing mechanismshown in Fig. 3, it was stated that the rate of discharge or reset couldbe varied at will by proper adjustment of resistance 33. This resettingoccurs whenever the energizing circuit E-E is interrupted. While therate of discharge may be determined by resistance 33, the actual amountof discharge depends upon the length of time the energizing circuit isinterrupted. If this time is long, practically all of the stored energywill be dissipated in resistance 33. Thus when the energiz ing circuitis re-established, charging of conenergy in the condenser, and thetime-required to charge the condenser will be the time necessary tocharge it from zero voltage to the critical voltage of tube 26. If thetime of reset'is short, condenser 24 will not be completely reset, andthus when the energizing circuit is reestablished, charging of condenser24 will start with a residual voltage on the condenser, and the periodtimed by the mechanism will be the period necessary to charge condenserfrom that voltage to the critical voltage of tube 28. The time periodwill be shorter by the amount of time that would have been necessary tocharge condenser 24 from zero voltage to the residualvoltage. It is thusapparent that the amount of reset depends upon thelength of time theenergizing circuit is interrupted. a

The above is the action of the apparatusif the energizing circuit isalways interrupted when condenser 24 has beencharged to some particularvoltage. In practice, as will appear later, the interrupting of theenergizing circuit may occur at all sorts of difierent voltages.Considering the operation of the device more in detail, it will 60appear that actual amount of discharge, while depending upon the lengthof time the energizing circuit is interrupted, also depends upon thevoltage ;to which the condenser has been charged when the energizingcircuit is interrupted. Thus, 'for example, a resetting impulse of acertain length of time, if occurring when the voltage of the condenseris 180 volts, resets the condenser to a voltage of '120; a resettingimpulse of the same length of time; if occurring when the condenser 70voltage is 150 volts, will reset the condenser to 100 volts. It thusappears that for a particular setting of resistance 33, resetting.impulses of a certain length of'time will reset the voltage of thecondenser to a certain fraction of its voltage. 7 5'This becomesapparent from'a consideration of "denser 24 will start with practicallyno stored the discharge equation of a condenser. equation is:

This

E0 is the voltage of the condenser when discharge was started; E: is thevoltage of the condenser after t seconds; e is the constant value 2.7183R is the value of the resistance 33; and C the cav C is of course fixed,and Thus pacity of the condenser. R is assumed set at some particularvalue.

it is obvious that for a particular value of t, the; condenser willalways be discharged to the same portion of the voltage. 7

Referring now to Fig. 2, it will be noticed that the vehicle actuateddevice consisting of ramp 1 is so arranged that circuit between wires l2and the circuit closed by ramps I and 3, relay 45 will be energized onlywhile the wheel of the vehicle is actually on the ramp, and consequentlythe length of time armature 5| is separated from contact I22 dependsentirely upon the speed of the vehicle. The energizing circuit of timingmechanism I2! is made through armature 5| and contact l22,and further,the energizing circuit of timing mechanism l2l is interrupted for alength of time which depends entirely upon the speed of the vehiclecausing such interruption. Re: ferring now to the above description ofthe operation of the timing mechanism, it becomes ap'' parent thattiming mechanism I2l, although giving the first vehicle a full 10seconds in which to cross the intersection, gives succeeding vehicles anadditional period which is dependent upon their speed, and consequently,succeeding vehicles are given just suflicient time to cross the inter-'section, instead of receiving a full, unnecessary 10 seconds. The fasterthe vehicle travels, the less the reset, and consequently the less isthe time given the vehicle. But, the faster a vehicl travels, the lesstime it needs.

The above would be the action if succeeding Vehicles continuallyapproach just before timing mechanism |2l is about to operate andseparate armature 90 from contacts 89 and 95. In practice, trafficrarely approaches in just that manner. For example, the second car mayapproach within a second or two from the time the first car approached.Thus, if there were no resetting. at all, the second car would receivepossibly 8 .or 9 seconds in which to cross the intersection,

which might be ample. But, the apparatus automatically takes care ofjust such a condition. 11' the second car approaches, say, after 2seconds, timing mechanism [2| will have been energized for only 2seconds and the voltage built up in its condenser will be quite small.Since, as ex-' plained above, the resetting does not reduce the voltageof the condenser by a certain number of volts, but instead reduces thevoltage by a certain portion of the voltage built up, the. amount ofreset will be very small, and the additional time given the secondvehicle, very small. 7

Timing mechanism M, constructed similar to timing mechanism l2l,performs the same operation for street A. V Cmmeotion-II.-The operationsdescribed above occur when the various switches are in the positionsshown in Figs. and 6. It may be seen from an inspection of Fig. 5 thatif switch I 4| is closed, relay 42 is continuously energized, there- 5by causing the right of way to return to A street not later than 39seconds after having been given to B street, if B street traiiic iscontinuous, or as soon as B street traffic ceases.

Connection IIL-It can be readily seen by in-- spection of Figs. 5 and'6that if the switches are as shown, except that switch M2 is closed, theoperation is as described under Connection II, except that theconditions described for A street and B street are interchanged.

Connection IV.It can be seen that with switches MI and i 32 closed, theright of way is granted alternately to each street and is held by eachstreet for any period between and 30 seconds. If no vehicles actuate theramp in a particular street during a period of 10 seconds, the 10 secondtiming mechanism functions to yield the right of way 10 seconds after itis granted. If, on the other hand, when said street is given the rightof way, vehicles operate either ramp in said street so that the 10second timing mechanism continually resets, the 30 second timingmechanism functions to yield the right of.

way seconds after it is granted.

Connection V.The circuit is so arranged that traffic actuated means,this can be accomplished by throwing switches M3 and M4 to their downpositions. Under these conditions, relays 42 and 6 are continuouslyenergizedand the energizing circuits of timing mechanisms M and IZI arecontinuously interrupted. "The'system will then function to give rightof way alternately to A street and B street for periods of 30 secondseach. Connection VI.-If it is desired to operate a system by hand, thiscan be accomplished by using switches I45 and M6. If both switches areopen, relays 34 and HI are deenergized, and the yellow light will beshown to both streets, as described previously. If switch I45 is .thenthrown to the down position, relay 34 will be energized and the A streetgreen light and B street red light will be shown. By. again openingswitch I45, the yellow light will again be shown to both streets. If,then, switch I46 is 50 thrown to the down position, relay I I I will beenergized, thus lighting the B street green light and A street redlight. By opening switch M6, the yellow light will again be shown toboth streets. Thus the lights can be operated'manually in any desiredmanner.

Connection VII .By closing switch Hi1, or by applying power to the twowires marked To fire headquarters, this will, through wires Hi9 and I50energize relay I 48. This will operate armatures B5) and H5, separatingthem from contacts 68 and i I4 respectively. This interrupts theenergizing circuits of both relays 3 1 and I l I and consequently bothof these relays become de-energized. This lights the yellow lightvisible from both streets. This feature is introduced to provide foremergency control either at the intersection or from a distant point.

Connection VIII .-It will be noticed that when right of way istransferred from A street to B 70 street, timing mechanism 86 times thewarning interval during which the warning signal or yellow light isshown. As mentioned before, this timing mechanism is the same as the oneshown in Fig. 3, and its resistance It! was assumed ad- 75.justed sothat it timed a period of 3 seconds.

if, for any reason, it is desiredto disconnect the 4. This differenceconsists in Wires EM and I52. Wire I52 is connected to one end ofresistance I9 as shown, while wire I5I may be adjusted along resistancel9 by tap H33. If circuit between wires I5I and I52 is closed, this willshunt out a portion of resistance l9, and consequently the period timedby the mechanism will be less than 3 seconds, and may be, for example, 1second. It will be noticed, furthermore, that if right of way istransferred from A street to'B street, through the operation of timingmechanism M, then the circuit between wires I5I and I52 is closedbecausetiming mechanism ll, in operating, causes armature I54 to touch contactI55. Thus the timing mechanism 8!] will provide a short warning period,namely, 1 second. If the transfer is caused by the operation of timingmechanism E39, then circuit between wires El and l52 is not closed, andthe warning signal provided by timing mechanism 30 will be 3 seconds inlength because no portion of its charging resistance has-i...beenshunted out. When the transfer of rightiof way is from B street to Astreet, timing mechanism Ml performs in a manner similar to timingmechanism 8%.

since traffic has ceased on A street, no longer warning signal need begiven because there are no vehicles on A street to be warned. The actionis similar when timing mechanism lZl transfers right of way from B to Astreet. If timing mechanism I39 transfers right of way from A street toY B street, it means that continuous A street traffic is beinginterrupted, and consequently a longer warning signal should be given sothat the vehicles in A street may have ample time to be brought to astop. The action is similar when timing mech-.

anism I31 transfers a right of way from B to A It will be noticed thatthe mechanism street. providesa long or a short warning period in accord with the needs of the traffic.

Connection IX.If all the switches are as:

shown in Figs. 5 and 6, except that switch ISO is closed, then as soonas right of way is given There is one slight difference in itsconstruction, and its complete wiring diagram is shown in Fig.

In this case the shunting out of a pore.- tion of the resistance isaccomplished through.

This Variable warning signal .is in to B street, armature Iil touchescontact MI and the energizing circuit E --E,of timing mechanism N2 ismade through wire H63, wire I64, switch I60, contact 5!, armature 5i andwire 52. This timing mechanism is similar to the one shown in Fig. 3,and we shall assume that its resistance I9 condenser will be discharged,and another 2 min.

utes of continuous B street right of way must be shown before timingmechanism I62 will operate.

Assuming there is no A streettraffic, .then right of way would remain onB street indefinitely, were it not for timing mechanism I62. After rightof Way has been showing for 2 minutes on B street, timing mechanism I62operates, causing armature I65 to. touch contact I66. This through wireI63, contact I66, armature I65, wire I61 and wire 13 energizes relay 42.It will thus be noticed that the operation of timing mechanism I62operates relay 42, thus performing the very same function that a vehicleapproaching on A street would have performed. If, when relay 42operates, B street traffic has ceased, right of way will be transferredto A street. If B street traffic has not ceased, then right of-way willeventually be transferred, as described above in the several cases,depending upon trafl'lc conditions in B street. We thus have a systemwhich, 15 in the event there is no traffic on one street, does, after acertain length of time, shift right of way to that street in order toallow pedestrians to cross. An additional important feature is that itdoes not arbitrarily transfer right of way at the end of the 2 minutes.It merely puts in a call on the street where the red light is beingshown, and the system then takes care of that call just as though it hadbeen caused by a vehicle approaching on A street. The fundamental objectof this system is to operate the signal lights in such away that trafficis controlled most efficiently. Timing mechanism I62 does not disruptthat operation but merely insures that right of way will eventually begiven to an opposing street even though there be no traffic upon it, inorder to allow pedestrians to cross the intersection.

If switch I68 is closed, timing mechanism I69 will be energized whenright of way is given to A street. This is accomplished through wire 8|,armature 82, contact I18, wire I1I, switch I68, energizing circuit EEand wire I12. Timing mechanism I69 is similar to timing mechanism I62,and performs the same function for B street that timing mechanism I62performs for A street. When timing mechanism I69 operates, it closescontact between armature I14, and contact I13, and thus through wireI12, contact I13, armature I14, wire I15, wires 48 and 41, operatesrelay 46.

Right of way is now being called to B street and will be transferred, asdescribed above in the several cases. Briefly reviewing the operation,it will be noticed that when right of wayhas been showing continuouslyon one street for 2 min- 50 ute's, right of way is called to the otherstreet, and will be transferred to that street after not more than 30seconds. With both switches I and. I68 closed at the. same time, and inthe absence of traffic on both streets, when right of 55 way has beenshowing continuously on one street for two minutes right of way iscalled to the other street and will be transferred to that street afternot more than thirty seconds, and after right of way has been showingcontinuously on the other 60, street for two minutes right of way iscalled back to the firststreet and will be transferred thereto after notmorethan thirty seconds'. Accordingly, in the absence of traflic, rightof way reverts between the streets at long intervals.

- Co nnection X.--In all of the above description, it was noticed thattiming mechanism 4I began to operate as soon as right of way appeared onA street. Experience has shown that it is, in

most instances, necessary to place the vehicle 70 actuated devices quitesome distance from the inters'ection. This occurs because vehiclesshould 'register'their presence some time before they reach the actualintersection. This will allow the mechanism to either give them time tocross gthe intersection, or if right of way is to be taken away from theapproaching vehicles, give them ample distance in which to stop.Suppose, for

' and the vehicles will be given time to cross the intersection; in thiscase, 10 seconds. If all the vehicles got into motion at once, this timewould be ample because the period provided should be sufficient to allowa moving vehicle, which has just actuated one of the vehicle actuateddevices,-

to cross the intersection. However, the vehicles will not all movesimultaneously. If, say, 10 vehicles are waiting, approximately 15seconds will elapse before the last vehicle in the line getsinto motion.Assuming there are no further operations of the vehicle actuatedcontrols, the vehicle protection timing mechanism on that street willnot be reset, and will, after 10 seconds, transfer right of way to theopposing street. This obviously will occur sometime before the lastvehicle in the line has begun to move, and several of the vehicles willbe stranded, without, however, leaving the system in such a conditionthat right of way'will again be given to the stranded vehicles withoutrequiring further actuation. It

is thus necessary to provide an initial timing perequired to allowwaiting vehicles to get into motiming mechanism is similar to the oneshown in Fig. 3.. When power is supplied to the two wires EE, .currentflows through Wire I11, relay I18, and wire I19, operating relay I18.This causes armature I to touch contact I 8|, and con.- denser I82 wouldbe charged through resistance I83. The amount of this resistance isvariable by means of contact I84. condenser I82 is a glow tube I83similar to the one previously described. When condenser I82 is chargedto the critical voltage of tube I83, the tube becomes conducting and theenergy stored in. I 82 discharges through tube I83 and relay I84,momentarily operating relay I84. This relay locks itself in throughcontact I85, armature I86, and wire I81. Contact I84 is mounted on arack-arm I85, mounted so that it can slide longitudinally. Thisrack-armv is pulled against stop I86 by tension spring I81. When switchI88 is moved so that it touches contact I89, current flows from wire I99through magnet I9I, switch I88, contact I89, and wire I92, and magnetI9I will be continuously energized. Magnet I9I The arby magnet I9I,causes finger I96 to engage the teeth I 91 of rack-arm I85. Thus if therackshunting V arm is moved to the left, the mechanism operated III 'When right of way is being given to B street, relay 34 is deenergizedand current flows from wire 39, armature 38, contact I98, wire I99,relay 200 and wire 20I, operating relay 200. Relay 200 operates armature202 and locks itself in through contact 203, armature 202, wire 204,contact 205, armature 206, and wire 201. Assume that one or more carsare waiting on A street, and right of way is about to be transferredfrom 13 street to A street. In the above description it will beremembered that timing mechanism 4| begins to operate as 'soon as rightof way is transferred to A street. With'switch I08 open, however, theenergizing circuit of timing mechanism 4| is interrupted and will not beclosed until relay Z88 operates, which will close the energizing circuitof timing mechanism 4| ,through wire 209, armature 2I0, contact 2, andwire 2 I2. Relay 208 does not operate immediately as Will appear fromthe following description. When right of way has been transferred to Astreet, relay 34 will be energized, which allows current to flow fromWire 39 through armature 38, contact 2I3, wire 2I4, wire I11, relay I18,wire I19, contact 2|5, armature 2|6 and wire 28I, operating relay I18.This establishes the charging circuit of condenser Wire 2I4, condenserI82, armature I80, contact I 8|, contact I84, resistance I83, contact2|5, ar-

mature 2I6, and wire 20I. Thus, the voltage of the supply is applied tocondenser I82 through resistance I83, and the voltage ofthe condenserwill begin'to build up. As assumed before, 10 seconds will elapse beforecondenser I82 is charged up to the critical voltage of tube I83.Although right of way is being given to A street, timing mechanism 4|has not begun to operate, and the vehicles waiting on A street are givenopportunity to get into motion and start across the intersection. Theyare in no danger of having timing mechanism 4| prematurely take awayright of way. After 10 seconds have elapsed, condenser I82 reaches thecritical voltage of tube I83 and the energy stored in condenser I82discharges through tube |83 and relay I84, operating armature I86 whichlocks in relay I84 through contact I85, armature I88, wire I81, contact2|5, armature 2I6, and wire 20L Relay I84 also or)- erates' armature2|1, causing it to touch contact 2|8. This allows current to flow fromwire 2|9, through contact 2I8, armature 2|1, wire 220, relay 208, andwire 201, operating relay 208. This closes contact between armature 2I0and contact 2| I, completing the energizing circuit of timing mechanism4|.

It thus appears that the waiting vehicles have been given a period of 10seconds in which to get into motion, and after this period, timingmechanism 4| provides the usual protection period, which of course isresettable by additional vehicles approaching on A street. The actionfrom now on is just as described in the above cases. When relay 208operates it causes armature 2I8 to touch contact 22 I, looking in relay208 through contact 22I, armature 2 I 0, wire 209, wire I05, contactI02, armature I0| and wire I04. At the same time relay 208 causesarmature 208 to separate from contact 205, interrupting the lockingcircuit of relay 200 which becomes deenergized. When relay 200 becomesdeenergized, armature 2|6 separates from contact 2I5, interrupting theenergizing circuit of timing mechanism I16, and relay I18 becomesdeenergized. This shunts adjustable resistance 222 through contact 223and armature I80 across the terminals of condenser I82, and any energystored there will be dissipated in resistance 222. If traflic approacheson B street, then eventually right of way will be transferred to Bstreet. The moment A street loses right of way, relay 34 becomesdeenerg-ized, establishing the energizing circuit of relay 200, whichoperates. The locking circuit of relay 200 is not completed until theend of the warning period. At the end of this period, timing mechanism80 operates, separating armature IOI from contact I02 which interruptsthe locking circuit of relay 208 which becomes deenergized, allowingarmature 206 to touch contact 205, and the locking circuit of relay 200is complete. The mechanism has now returned to the condition at thebeginning of operations.

Timing mechanism 224 performs the same function for B street that timingmechanism I18 performs for A street. Similarly switch I24 must beopened. Switch 225 when moved to touch contact 22%? cause magnet 221 tobe continuously energized through wires 228 and 229. The armature Z38,operated by magnet 22?, is similar to the armature operated by magnetHM, and is arranged to engage the teeth 225i of rack-arm 232. Thisrack-arm is pulled toward stop 283 by spring 288. When right of way isbeing given to A str et, relay III is deenergized, and through wire 235,wire contact 231, armature 18 and wire i9, energizes relay 238. Thisrelay locks itself in through contact 239, armature 240, wire 24I,contact 242', armature 243 and wire 244. When right of way has beentransferred to B street, current flows from wire 19 through armature I8,

contact 245, wire 248, relay 281, wire 1388, contact 249, armature 258,and wire 235, operating relay 241. This establishes a circuit from wire19, armature 18, contact 245, wire 246, condenser 25I armature 252,contact 253, contact 254, relay 255, contact 2'49, armature 250 and wire235. Assume that rack-arm 283 is so adjusted that the amount ofadjustable resistance 255 is of such a value that 10 seconds arerequired to charge condenser 25I up to the critical voltage of tube 258.After 19 seconds haveelapsed, the energy stored in con denser 25!discharges through tube 258 and relay 251. Relay 251 locks itself inthrough contact 258, armature 259 and wire 288. At the same time acircuit is established through wire 28L contact 282, armature 263, andwire 28 i, through relay 265, and throughwire 244. When relay 285operates it looks itself in through contact 268, armature 291 and wire268, at the same time through contact 289 and wire 218 completes theenergizing circuit of timing mechanism I2I. The operation of the devicefrom this time on is similar .to the operation of timing mechanism I16,except that the functions for A and B streets are interchanged.

The above connection provides for an initial period during whichvehicles may get into motion. While this may be satisfactory, in a greatmany installations, the device may occasionally be inefficient becausethe timing period, although adjustable manually, is fixed. Thus if, forexampie, 5 vehicles are waiting, the 10 second period may be just right.If more than 5 are waiting, a longer period may be desirable, and thenagain, if less are waiting, a shorter period would be ample. Thus it isdesirable to provide an initial period that is proportional to thenumber of vehicies wait ng. This may be accomplished on .A street, forexample, by closing switch Z'II and moving switch I88 so that it touchescontact 212. When right of way is being given to B street, and

no vehicles are waitingon A'street, relay 288 will be energized, asdescribed previously, and so will magnet I8I, although the energizingcircuit of magnet I8I is somewhat different, being made through wire21-3, contact 2I5, armature 2I6, and wire 28I. As will appear later,rack-arm I85" is resting against stop I86. 1 Everytime a vehicleapproaches on A street, it momentarily operates relay I29, allowingcurrent to flow from wire 214., contact 215, armature 218, wire21.1.,contact 218, armature 219, wire 288, switch 21I, magnet 28l,and'wire I98, momentarilycperating magnet 28I.. This attracts armature282--which is similar. to the armature operated 'by magnet I8I. Finger283 engages the teeth of rack-arm I85 notching the rack-arm forward bythe "distance of one tooth. Magnet I8I is so arranged that when therack-arm is moved forward the distance of one tooth, finger I96 engagesthe teeth and prevents the return motion of rack-arm I85. Thus, magnet28I is momentarily energized every time a vehicle causes relay I28 tooperate, and the rackarm I85 is moved a distance proportional to thenumber of vehicles that have approached on A street, while right of wayis being given to B street. This provides that, since contact I84 moveswith rack-arm I85, the amount of resistance I83 in series with condenserI82 is proportional to the number of vehicles waiting, and when timingmechanism I18 begins to time, the period timed by it will beproportional to the number of waiting vehicles. The operation of thedevice otherwise is the same. At the end of the period timed bymechanism I18, relay I84 operates and thus causes relay 208 to operate,all as described previously. At the same moment, relay 288 becomesdeenergized and armature 2I8 separates from contact 2I5. Thisdeenergizes timing mechanism I18, but, in addition, also deenergizesmagnet I9I, allowing finger I98 to move out of engagement with the teethof rack-arm I85, and rack-arm I85" is pulled against stop I86 by springI81. Thus the mechanism has returned to its starting position, so thatthe next time vehicles register their presence on A street while Bstreet is being given right of way, will again provide themselves withan initial period proportional to their number. It will furthermore benoticed that when right of way appears on A street, armature 219separates from contact 218, interrupting the notching circuit of magnet28l, and thus the initial period will not be increased by furthervehicles registering on A street.

The operation of timing mechanism 224 which provides the initial periodfor B street, can be adjusted similarly by closing switch 284 and movingswitch 225 so that it touches contact 285. Thus, whenever a car operatesone of the Bstreet ramps, relay 45 operates momentarily, allowingcurrent to flow through wire 288, contact 281, armature 288, wire 288,contact 288, armature 29I, wire 292, switch 284, magnet 293, and wire228. Thus, magnet 293 is operated every time relay 45 operates. Magnet283 operates armature 294,

notching rack-arm 232 in a manner similar to the notching of rack-armI85. It will again be noticed that vehicles registering on B street,after right of way has appeared on B street, do not increase the initialperiod because the notching circuit is interrupted at contact 288 andarmature 29I, which are caused to separate when relay II I operates.

While the above mechanism provides for an 7 5 initial period that isproportional to the number of vehicles waiting it may, under certain maybe accomplished for, A street by-closing switch 285, and as aconsequence the notching circuit is not interrupted whenvright of way,appears on A street. If further vehicles approach on A street, theywill continue to operate gmagnet 28l, moving rack-arm I85 'so as toincrease the charging resistance. Switch 296 is provided to perform thesame function for B street.

From the foregoing, it will be'seen that a traffic control system isprovided which operates-in such a way that:

1. The right of way is given successively to several traffic lanes in anorder which may be predetermined, but in such a way that thelength oftime one lane retains the right of way is dependent upon either theapproach ;of vehicles in said lane or upon approach of vehicles in oneor more other lanes,'or upon both.

2. That a traflic lane which does not require the right of way cannothold itto the disadvantage of one which does. v v

3. That a vehicle whoseprogress is prevented by a continuous stream ofopposing traffic may not be required 'to wait more than a predeterminedperiod of time, and that not later than the end of said predeterminedperiod of time 'said vehicle is given right of way for a period of timesufiicient for it and following vehicles tocross the intersection,

4. That interfering lanes of traffic shall :not be-given right of waysimultaneously.

5. That a vehicle which has passed an actuating means is protectedagainst opposing 'tramc for a period of time sufficient to permit saidvehicle to pass the intersection "of the traffic lanes.

6. That a vehicle which approaches an intersection on any lane oftraflic is .given immediate right of way on condition, and only oncondition that there be no opposing traflic in or immediatelyapproaching the intersection.

7. That when. a vehicle is not given immediate right of way or has rightof way taken trom it, before it has had .sufilcient time to cross theintersection, the system will be left in :such a condition that right ofway will return to the delayed vehicleas soon as traflic-conditions permit.

8. That periodically right of way shifts to another lane even thoughthere be .no vehicular traffic on that lane, in orderto allowpedestrians to cross the intersection.

9. That when the signal means and timing system is disconnected from thetrafiic factuated means, right of way maybe given .successively to thevarious trafiic lanes according to,

a predetermined sequence and toeach lane for a predetermined timeinterval. 1 10.. That the signal means may be disconnected from thetraffic actuated means and timingsysa 12. That the warning signal may beinterposed between. right of way and stop signals, the timing of saidwarning signal being in accordance with the traflic conditions existingat the moment.

13. That each vehicle is protected against opposing traflic for a periodcommensurate with its speed.

14. That if one or more vehicles, after passing the actuating means, donot receive right of way immediately, they will be protected againstopposing traffic when they do receive right of way, for a period of timesuflicient to allow the last of the waiting vehicles to get started.

Summarizing certain of the salient features of the present invention, itwill primarily be understood that an extremely efficient traffic controlsystem is herein provided and by means of which among others, theseveral objects of the invention as specifically afore referred to areachieved. These objects to a great extent are 1 accomplished by a numberof factors which for the purpose of convenience may be identified (a) asvariable amber, (b) periodic calls, (0) variable increment, and (d)speed proportional control.

Dealing primarily with the question of variable amber, it will beunderstood that in the case of traffic approaching the intersectionalong one vehicle lane, and with no traffic in the second vehicle lane,there will be no necessity for a relatively delayed amber or transferperiod. Accordingly, and by means of the present disclosure, the systemwill serve to transfer right of way to the vehicle lane over whichtraffic is approaching the intersection with a minimum delay period. Onthe other hand, where need for this delay period exists, as forinstance, where there is a continuous stream of tramc along the vehiclelane which has the right of Way and vehicles on the intersecting laneare awaiting the right of way, the transfer of right of way will only becompleted after a maximum i. e. a' threesecond delay period. 45 Dealingwith the question of periodic call, it will be observed that by means ofthe present invention, a functioning of the vehicle actuated control ineffect occurs periodically even in the absence of vehicles. Moreparticularly, as 50 set herein for example, even if there is no.

traific along one vehicle lane and continuing traffic along the othervehicle lane, the right of way over the latter will be interrupted atthe end of a two minute and thirty second period for minimum of tenseconds. This will allow pedestrians to cross. The reason for this willreadily be understood in that the two-minute timers in the event ofcontinuing traffic along one lane have their functioning qualified bythe thirty ,60 second timer, the former permitting the initiation offunctioning of the latter after two minutes have elapsed. In the case oftraffic over neither lane, the two-minute timers would of course operateperiodically to permit pedestrians 65 to traverse the intersectionwithout fear of traffic. It will, of course, be appreciated that thisperiodic call is entirely qualified in the case of continuous trafficapproaching the intersection over both vehicle lanes. 7Q With regard tothe variable increment feature, it is understood that as previouslybrought out there is grave danger in the case of a number of vehiclesawaiting right of way and all of which have operated the vehicleactuated con- 75 trol due to the necessary sluggishness of the lastvehicles of this group. Consequently the right of way once accorded thisgroup of vehicles would be liable to be transferred before the last ofthe vehicles could negotiate the intersection. This difficulty, however,is anticipated by means of the present disclosure in that a timerfunctioning after right of way has been accorded such a vehicle groupdoes not begin actually until a time period has elapsed proportionate tothe number of vehicles which are awaiting the transfer of right of way.Accordingly, the last vehicle of this group will still be accorded aminimum right of way time period to negotiate the inter-T section. As apractical matter, it may of course be in many instances desirableaccording to the present invention to manually set this portion of theapparatus to approximate for this condition, but in any event, the timefactor will be adequate and the system will take into account thosevehicles arriving just after right of way has been accorded and whichvehicles necessarily slow down as they become part of the group which isnegotiating the intersection.

With respect to the speed proportional control, it will be understoodthat by the present disclosure, the timer resetting is not simplyeffected in an arbitrary manner which might in one instance result inundue delay to transfer of right of way and in another instance resultin the transfer being effected at such an early moment as to trap avehicle at the intersection, but that the resetting of this timer willactually be in proportion to the speed of the vehicle which is.approaching the intersection.

Obviously, one or more of these factors might under certain instances bedispensed with and the several units of the apparatus while preferablyembodying a construction substantially of the type illustrated anddescribed, might be changed in numerous respects without departing fromthe spirit'of the invention as defined by the claims.

I claim:

1. A traffic control system for interfering traffic lanes including asignal operable to accord and interrupt right of way to the severallanes, vehicle actuated devices in the lanes, a timer connected to saidsignal and devices adapted to operate said signal so as to accord andinterrupt right of way over said lanes, means forming a part of saidtimer to cause each accord of right of way to be maintained for minimumand up to maximum right of way periods according to 'actuations of thevehicle actuated devices, and

means forming a part of said system and acting only in the event of thevehicle actuated device of one lane remaining non-actuated for a periodof time in excess of such maximum period to cause transfer of right ofway for a certain period to the lane of said non-actuated device even inthe absence of traffic.

2. A traific control system including, in combination, signalling meansto be disposed adjacent the point of intersection of traffic lanes andoperable to accord and interrupt right of way to the several lanes, atimer for operating said signalling means to accord and interrupt rightof way over said lanes, a traffic actuated device disposed in each lanein advance of said intersection and connected to said timer to governthe operation thereof, timing means forming a part of said timer andacting in response to a functioning of any one of said traflic actuateddevices to accord, through said signalling means, right of way to thelane of said one device for a minimum period of time, resetting meansfor said timing means and acting in response to a functioning of saidone device during such right of way period to cause said timing means tosupplement said right of way period by a further time interval inverselyproportionate to the speed of the traflic which actuated said device,and means acting periodically in the absence of trafiic actuated deviceactuation in one lane to transfer to such lane right of way indicationfor a period of time.

3. A traffic control system including, in combination', a signallingmeans for according and interrupting right of way to traffic moving overintersecting lanes, a timer connected toand controlling the operation ofsaid signalling means, a traffic actuatable device for each lane andconnected to said timer to cause said signalling means to accord,responsive to actuation of said device'in either one lane, right of wayto such one lane, means forming a part of said timer for maintaining theright of way so accorded to any lane for at least a minimum period andin the absence of actuation in any remaining lane for maintaining rightof way beyond said minimum, and means forming a part of said timer andfunctioning in such absence of actuation of said device in any remaininglane after a period, always longer than said minimum and beginningsubstantially with said accord of right of way to automatically simulatean actuation of said device for said one of said remaining lanes wherebyto transfer right of way through said means to the lane of the lastmentioned controller.

4. A trafiic control system including in combination a'signalling meansfor according and interrupting right of way to traffic moving overintersecting lanes, a timer connected to and controlling the operationof said signalling means, a 40 traffic actuatable device for each laneand connected to said timer to cause said signalling means to accord,responsive to actuation of said device in either one lane, right of wayto such one lane, means forming a part of said timer for maintaining theright of way so accorded for at least a minimum period, means forming apart of said timer and functioning in response to further deviceactuation in such one lane during the right of way for such one lane forassuring maintenance of right of way up to a maximum period after anyactuation in another lane, and means operable only after a period ofsuch right of way, with absence of actuation in the other lane, longerthan said maximum to automatically cause I transfer of right of way tosuch other lane.

5. In a trailic control system for interfering traffic lanes, a signaloperable to accord and interrupt right of way to the several lanes,traffic actuated devices for the lanes, a timer connected to said signaland including control means for such lanes and connected to such devicesand operablein response to actuation of such traflic actuated' devicesto operate said signal so as to accord'right of Way to either one lanein which such actuation has first occurred, and to interrupt right ofway in the other lanes, and means acting only after right of way hasbeen accorded to any one lane for a predetermined time, withoutactuation in any other lane, beginning substantially with such accord'ofright of way to said one lane to automatically produce the same effecton saidcontrol means as that of actuation in another lane.

6. In a traffic control system for interfering traflic lanes, a signaloperable to accord and interrupt right of wayto the severallanes,trafiic actua'ted devices for the lanes, a timer connected to saidsignal and including control means for such lanes and connected to suchdevices and operable in response to actuation of such traffic actuateddevices to operate said signal so as to accord right of way to eitherone lane in which such actuation has first occurred and to interruptright of way in the other lanes, means forming a part of said timer tocause such accord of right of way to be maintained for at least aminimum period and to be extendible by actuations on said one lane up toand within a maximum period initiated by any actuation occurring onanother lane, and means operating'only after right of way has beenaccorded to said one lane for a pre-de-' termined period of absence ofactuation on another lane, said period beginning substantially with suchaccord of right of way to said one lane, to affect said timer like suchan actuation on another lane so as to assure transfer of right of wayfrom said one lane to such another lane within said predeterminedmaximum period thereafter.

7. In a trafiic signal system for interfering traffic lanes, a signaloperable to accord andinterrupt right of way to the several lanes,vehicle actuated devices in the lanes, a controller connected to saidsignal and devices for operating said signal in response to actuationsof said vehicle actuated devices so as to accord right of way to any onelane in which such actuation has occurred and to interrupt right of Wayin the interfering lanes and means acting only in theevent ofa-relatively prolonged predetermined period of absence of actuation ofthe vehicle actuated device in such interfering lanes, said periodbeginning substantially with such accord of right of way to the said onelane, to simulate a functioning of such device in one of the interferinglanes to cause transfer of right of Way from said one lane to the lastsaid interfering lane.

8. A traflic control system including, in combination, signalling meansto be disposed adjacent an intersection of trafiic lanes and. operableto accord and interrupt right of way to the several lanes, a timer foroperating said signalling means to accord and interrupt right of wayover said lanes, trafiic actuated devices in said lanes and in advanceof said intersection and connected to said timer to cause the latter tofunction in response to actuation of the former, timing means forming a,part of said timer and acting through operation of said signalling meansto provide alternately in such lanesupon actuation of the devices inboth lanes right of way periods variable between minimum and maximumlimits, said minimum right of .way periods being extendible through saidtiming means and through operation of said traffic actuated devices upto said maximum periods, means acting while right of way is accorded toone lane and in the absence of operation of the traiiic actuated devicein the other lane, to extend the right of way period in said one lanebeyond said maximum, and means acting only thereafter, and despitecontinued absence of operation of the trafiic actuated device in suchother lane, to automatically transfer right of Way to such other lane.

9. A trafiic control system for a plurality of of the latter, the timerincluding relay means for each lane and connected to the correspondingtrafiic responsive means for repeating to the timer the efiect oftraffic actuation of the traffic responsive means and cooperating withthe timer to store the effect of actuation until the timer is incondition to accord right of way to the actuating trafiic, said timeralso including means operable upon operation of such relay means toaccord right of way alternately to the lanes between minimum and maximumperiods in accordance with traffic actuations, and means associated withsaid timer but independent of the maximum timing means mentioned and.operable only after right of way has been accorded to any one lane for apredetermined period, and in absence of actuation on the other lane, tooperate said relay means for such other lane to produce the same effecton the timer as that of traffic actuation on said other lane.

10. A traffic control system for a plurality of interfering trafliclanes comprising signalling means adapted to accord and interrupt rightof way in such lanes, traffic responsive means in each of said lanes, atimer connected to the signalling means and traflic responsive means togovern the former in accordance with actuations of the latter bytrafiic, the timer including relay means for each lane and connected tothe corresponding traffic responsive means for operation by trafiicactuation of the latter, means associated with said relay means andcooperating with the timer to maintain said relay means so operated inthe event it is operated momentarily while right of way is interruptedin its corresponding lane and until the timer causes the signallingmeans to accord right of way to the lane of such actuation, said timeralso including minimum timing means to maintain the right of way for aminimum period when accorded and adapted to prolong right of way beyondthe minimum by actuations in the same lane, and also including maximumtiming means for providing a limit to such prolongation, means forming apart of said timer cooperating with said minimum and maximum timingmeans to cause said signalling means after such minimum and suchprolongation, if any, to interrupt right of way in one lane and accordright of way to another lane when the relay means of the latter isoperated, and super-maximum timing means also forming a part of saidtimer and active, to time, while the right of way is accorded to any onelane, a period longer than said maximum at the end of which it operatessaid relay means for the other lane whereby the timer will be actuatedto accord right of way subsequently to said other lane even in theabsence of trafiic actuation on said other lane.

CHARLES D. GEER.

